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MQ-MAS: Sensitivity Enhancement
User Manual Version 002
BRUKER BIOSPIN
235 (327)
Three pulse sequence and coherence transfer pathway for the 3Q MAS experi-
ment with z-filter (mp3qdfs.av). Excitation pulse
p1
is the same as for mp3qzfil.av,
P4
is a central transition selective 180° pulse (usually 2*p3). Delays
D0
is the in-
cremented delay for t
1
evolution. Delays
D10
or
D11
must be incremented propor-
tional to
D0
. Power level and duration of the sweep
P2
must be optimized. Phase
lists are as follows, 2D data are acquired in QF mode, which means that no phase
incrementation is required:
ph1 = 0 30 60 90 120 150 180 210 240 270 300 330
ph2 = 0
ph3 = 0*12 90*12 180*12 270*12
receiver = {0 270 180 90}*3 {180 90 0 270}*3
Initial parameter values are listed in
. A few of these parameters need
further explanation:
D6
:
Is calculated as (1s*
L1
/
CNST31
)-(
P4
/2)-(
P2
/2). This ensures that the delay
from the centre of the sweep to the middle of the 180° pulse is an integer multiple
of the rotor period.
L1
must be set so that
D6
becomes long enough for a full echo
to build up. If we assume the FID has decayed after 3 ms, spinning frequency is
25 kHz, and the 90° pulse is 20 µs, then
L1
should be between 70 and 80 so that
D6
is between 2.77 and 3.17 ms.
P2
:
Is calculated as 1s/(
CNST31
*
L0
). The duration of the sweep can be adjusted
depending on T
2
of the sample. The sweep should not be longer than one rotor
period, for many samples you may find that a quarter of a rotor period or even less
is sufficient.
In
ased
the values of the two parameters
D6
and
P2
are greyed, because they
cannot be set anymore. They are calculated in the pulse program from the param-
eters explained below, which must be set accordingly:
L0
:
Defines the fraction of a rotor period for the duration of the sweep
P2
, usually
between 1 and 8.
L1
:
Defines
D6
to be an integer number of rotor periods.
The sweep will be defined by further parameters:
CNST1
:
Start frequency (in kHz) of
the sweep; the sweep should start slightly off
resonance, usually 30 to 50 kHz from the resonance of the central transition.
CNST2
:
End frequency (in kHz) of the sweep; the sweep should cover the satellite
transition, but this is often broader than the band width of the probe of approxi-
mately 1 MHz. Therefore, it does not make sense to have this value bigger than
1000.
Содержание Solid State NMR
Страница 1: ...Version Bruker BioSpin think forward NMR Spectroscopy Solid State NMR 002 AVANCE Solids User Manual...
Страница 8: ...8 BRUKER BIOSPIN User Manual Version 002 Contents...
Страница 14: ...14 327 BRUKER BIOSPIN User Manual Version 002 Test Samples...
Страница 104: ...104 327 BRUKER BIOSPIN User Manual Version 002 Practical CP MAS Spectroscopy on Spin 1 2 Nuclei...
Страница 118: ...118 327 BRUKER BIOSPIN User Manual Version 002 Basic CP MAS Experiments...
Страница 122: ...122 327 BRUKER BIOSPIN User Manual Version 002 FSLG HETCOR Figure 8 3 The ased Display...
Страница 154: ...154 327 BRUKER BIOSPIN User Manual Version 002 Proton Driven Spin Diffusion PDSD...
Страница 172: ...172 327 BRUKER BIOSPIN User Manual Version 002 SUPER Figure 13 3 The Acquisition Parameter Window eda...
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Страница 192: ...192 327 BRUKER BIOSPIN User Manual Version 002 Symmetry Based Recoupling...
Страница 212: ...212 327 BRUKER BIOSPIN User Manual Version 002 Relaxation Measurements...
Страница 270: ...270 327 BRUKER BIOSPIN User Manual Version 002 Double CP...
Страница 284: ...284 327 BRUKER BIOSPIN User Manual Version 002 CRAMPS 1D Figure 22 9 WPMLG CRAMPS After Optimization Digital Acquisition...
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